Alignment Question - PeachParts Mercedes-Benz Forum

JamesDean · #1 01-20-2013, 06:59 PM

Hey everyone,

So I got an alignment done last weekend and everything was fine for most of the week. Then towards the end of the week it started to pull to the right and generally piss me off. The front end on the 300D was rebuilt by the previous owner back in 2010 and drove pretty well.

I was going to go back up to the alignment shop Saturday but I accidentally slept in and missed the closing time.

Here is my alignment sheet from the shop, any thoughts on it?

I dont quite know much about alignments or which degree value corresponds to what aspect. They are the only shop that is open on the weekend and one of three in the area that do Mercedes.

Why are the values on the left not equal to values on the right? Especially in the first item? I believe that is caster?? and has to do with left/right steering? Shouldn't those two numbers be equal, would not a discrepancy cause pulling to one side or another?

I have to have my 190E aligned as well. It has all new suspension AND steering box....

Skippy · #2 01-20-2013, 08:20 PM

I had to get out my ASE A4 study book for this one.

On the front, your cross caster should be giving you a slight pull to the left while your cross camber should be pushing you right. The slightly higher camber on the right is pretty normal in manufacturer specs for LHD cars, since it will keep you going straight on a road crowned to the right. On the rear, the cross caster is wanting to push the rear of the car to the left. All the numbers are within spec, but your front and rear caster are conspiring to give you a pull. Also, two degrees negative camber seems like a lot to me unless you drive like a thrill seeking speed demon (IOW like me

). I don't know how much adjustability is in the 126 rear suspension, so your tech may have to try to balance it out at the front.

JamesDean · #3 01-20-2013, 09:16 PM

Quote:

Originally Posted by Skippy

I had to get out my ASE A4 study book for this one.

On the front, your cross caster should be giving you a slight pull to the left while your cross camber should be pushing you right. The slightly higher camber on the right is pretty normal in manufacturer specs for LHD cars, since it will keep you going straight on a road crowned to the right. On the rear, the cross caster is wanting to push the rear of the car to the left. All the numbers are within spec, but your front and rear caster are conspiring to give you a pull. Also, two degrees negative camber seems like a lot to me unless you drive like a thrill seeking speed demon (IOW like me

). I don't know how much adjustability is in the 126 rear suspension, so your tech may have to try to balance it out at the front.

Thanks for the info!

Also the car in question is a 1991 300D 2.5.. I am not sure why they used a 126 chassis for the specifications.. When I took the 190E there previous it was aligned to "93 140 and all" specification.

SD Blue · #4 01-20-2013, 10:47 PM

Did you check your tire pressures? If everything was fine, most of the week, it may something as simple as low pressure in a tire. I've noticed that a sudden cold front tends to undo tire pressures, at times. I'm not sure why that is and some tire brands seem a little more prone to this problem.

JamesDean · #5 01-21-2013, 05:54 PM

I hadnt thought about tire pressures but I can check.

I was on the turnpike today and found that in the center lane, the car pulled to the left and I had to compensate to the right.

When I was in the right lane, I found the opposite. It pulled to the right and I had to compensate left.

It was not HORRIBLE but it was noticeable enough to me that it was annoying.

It absolutely infuriates me to the point of just throwing parts at the car..which is what I did with the 190E. It still needs an alignment but the steering is SOLID and has SIGNIFICANTLY improved over its previous state.

scottmcphee · #6 01-22-2013, 12:14 AM

Sure it's not a worn center link or idler arm bushing? Iknow, the suspension shop is supposed to check for stuff like this, but did they inspect all links closely for wear?

JHZR2 · #7 01-22-2013, 12:38 AM

Worn parts or slop in the steering box are my first thoughts.

Did they use the spreader bar to do the alignment? If not, I suppose the loading may not be realistic.

JamesDean · #8 01-22-2013, 08:26 AM

Quote:

Originally Posted by scottmcphee

Sure it's not a worn center link or idler arm bushing? Iknow, the suspension shop is supposed to check for stuff like this, but did they inspect all links closely for wear?

I am not sure about this. I would imagine they checked these but cannot be sure. I had the 190E's idler arm bushing replaced. I am not sure the 300D has been. I know the lower control arm bushings and ball joints were done.

Here are my records actually:
https://docs.google.com/file/d/0By8MqLgsKlwXdG5HZUlCbEkwc1k/edit

JamesDean · #9 01-22-2013, 08:29 AM

Quote:

Originally Posted by JHZR2

Worn parts or slop in the steering box are my first thoughts.

Did they use the spreader bar to do the alignment? If not, I suppose the loading may not be realistic.

Thats what my thoughts were too. Especially since I just went through a similar ordeal with my 190E. I replaced everything except the center steering link.

The previous owner replaced the shocks, lower control arm bushings and ball joints.

The tie-rods, center link, idler arm and steering box are, presumable original or replaced prior to the previous owner as I did not see records on those.

I don't think they used a spreader bar. In the past I inquired about that they seemed to have no idea on that topic.

shertex · #10 01-22-2013, 09:03 AM

My understanding is that an alignment cannot be done PERFECTLY right without the MB spreader bar....which no one but MB seems to have.

I got a lifetime alignment at Firestone....they can get it very close (I found that the have to pull the specs from the VIN, NOT the model number), and there's one of their techs in particular who has a good deal of experience with alignments. One of the things I like about the lifetime alignment is that, if the alignment changes, you simply get it redone at no cost.

raysorenson · #11 01-22-2013, 09:48 AM

It looks like you got a pretty solid alignment for a 126

Maybe even a 124 too!

The first value you mention as not being even is fine. It's caster, and a good tech knows to put a little less caster on the left. Generally drivers spend more time to the right of the crown of the road which causes a drift to the right. This is offset by putting less caster on the left. All cars come from the assembly plant like this. The pull moving from the left to right when you change lanes is probably because the lanes have different camber. The right lane should lean more to the right, causing more of a drift to the right.

I'd be more into having camber, the second angle being perfectly even. A difference in camber can cause a pull, but it's sort of fuzzy. A .3* delta in camber from the l to r isn't really big and the tire is a huge factor in whether or not camber will cause a pull. A 195/65/15 tire can deal with a camber delta better than a 245/45/1X tire as far as a pull is concerned.

Not using the toe bar will skew your front toe measurement. You really have less toe in the front than is indicated. The toe bar isn't a must, but I suggest compensating. The tech can add a little extra toe, or he can spread the front tires by hand with a modest amount of force, say, 20#, and see if toe is in specs while pushing. The thing about toe in on the front is that it helps with cross wind and road camber stability. If the road is tilted to the right, the weight of the car will slightly shift to the right putting more weight on the rf tire. The more toe in this tire has, the more it will resist allowing the car to drift to the right. The opposite is true for the rear axle. If there's negative toe on the rear and you're still driving on the previously mentioned road, as weight shifts to the right, the rear axle will drift to the right, preventing the car from drifting right. It's important to mind the relationship of front and rear toe if you don't like your car pulling in a different direction every time you change lanes.

Rear camber is a function of rear ride height. The '91 300d sits pretty low and will have corresponding negative camber. Negative camber does help cornering traction but not straight line traction. It's not that big of a deal but it will wear tires. Replacing the rear lower control arm bushings and the bushings in the rear knuckle where the LCA attaches might help if they're worn but the only way to adjust rear camber is to buy the Kmac bushings which cost 360-400 shipped.

Throwing parts? Throw them all at it. In a perfect world with unlimited funds, replace every piece of rubber on the front and rear ends. If your idler arm bushings aren't pretty new, I bet there's some play. As a front end guy, I have zero tolerance for idler arm slop. I like fresh LCA bushings and ball joints too. I'd replace them every 100k regardless of condition on a W124. Steering gear slop, while annoying, does not affect your alignment.

JamesDean · #12 01-22-2013, 09:55 AM

Quote:

Originally Posted by raysorenson

It looks like you got a pretty solid alignment for a 126

Maybe even a 124 too!

The first value you mention as not being even is fine. It's caster, and a good tech knows to put a little less caster on the left. Generally drivers spend more time to the right of the crown of the road which causes a drift to the right. This is offset by putting less caster on the left. All cars come from the assembly plant like this. The pull moving from the left to right when you change lanes is probably because the lanes have different camber. The right lane should lean more to the right, causing more of a drift to the right.

I'd be more into having camber, the second angle being perfectly even. A difference in camber can cause a pull, but it's sort of fuzzy. A .3* delta in camber from the l to r isn't really big and the tire is a huge factor in whether or not camber will cause a pull. A 195/65/15 tire can deal with a camber delta better than a 245/45/1X tire as far as a pull is concerned.

Not using the toe bar will skew your front toe measurement. You really have less toe in the front than is indicated. The toe bar isn't a must, but I suggest compensating. The tech can add a little extra toe, or he can spread the front tires by hand with a modest amount of force, say, 20#, and see if toe is in specs while pushing. The thing about toe in on the front is that it helps with cross wind and road camber stability. If the road is tilted to the right, the weight of the car will slightly shift to the right putting more weight on the rf tire. The more toe in this tire has, the more it will resist allowing the car to drift to the right. The opposite is true for the rear axle. If there's negative toe on the rear and you're still driving on the previously mentioned road, as weight shifts to the right, the rear axle will drift to the right, preventing the car from drifting right. It's important to mind the relationship of front and rear toe if you don't like your car pulling in a different direction every time you change lanes.

Rear camber is a function of rear ride height. The '91 300d sits pretty low and will have corresponding negative camber. Negative camber does help cornering traction but not straight line traction. It's not that big of a deal but it will wear tires. Replacing the rear lower control arm bushings and the bushings in the rear knuckle where the LCA attaches might help if they're worn but the only way to adjust rear camber is to buy the Kmac bushings which cost 360-400 shipped.

Throwing parts? Throw them all at it. In a perfect world with unlimited funds, replace every piece of rubber on the front and rear ends. If your idler arm bushings aren't pretty new, I bet there's some play. As a front end guy, I have zero tolerance for idler arm slop. I like fresh LCA bushings and ball joints too. I replace them at 100k regardless of condition. Steering gear slop, while annoying, does not affect your alignment.

Thanks for the info Ray! I wish you were closer so you could drive the car and see how it feels. Maybe I'm just overly sensitive to these things!

I dont think the idler arm bushings are new or even relatively new. Probably never been replaced. So maybe I'll have those done. Its fairly cheap. The front LCA rubber and ball joints are only a few years old so and they have less than 30k on them I would say.

With regard to the rear camber, there are cheaper solutions than the Kmac arms. I have some arms installed on my 190E that were <100 total.

Perhaps after this weather clears up and I can get the 190E aligned and back on the road, I'll send the 300D down for an idler bushing and general checkup.

Zulfiqar · #13 01-22-2013, 10:13 AM

The only best way of alignment is to note down the alignment specs from the build code - e.g my car is a W124.131 - which calls for a different alignment than the older 2.5 turbo - WHY??? I have no idea - maybe because the E300D sits lower at the front and uses ET44 wheels.

The spreader bar is mandatory to literally force the wheels apart - otherwise you end up with a squirrelly feel and the car will want to roll askew as a slight toe change in the front of a MB dictates a lot of change in camber.

JamesDean · #14 01-22-2013, 10:17 AM

Quote:

Originally Posted by Zulfiqar

The only best way of alignment is to note down the alignment specs from the build code - e.g my car is a W124.131 - which calls for a different alignment than the older 2.5 turbo - WHY??? I have no idea - maybe because the E300D sits lower at the front and uses ET44 wheels.

The spreader bar is mandatory to literally force the wheels apart - otherwise you end up with a squirrelly feel and the car will want to roll askew as a slight toe change in the front of a MB dictates a lot of change in camber.

Can you elaborate on the "roll askew" portion? I'm fairly certain they did not use a spreader bar...

Zulfiqar · #15 01-23-2013, 11:24 AM

when aligned correctly the wheels sit straight, true and centred when driving down the road, a bit off on toe on these MB and your camber also goes to whack so you then end up with a tyre trying to roll either outwards and also leaned out.

You can imagine the setup like 2 motorcycles (due to the excessive caster on our cars) if you tilt the handlebars on the bike the wheel slops to one side - this is what im calling rolling askew if you have bad toe on your car, the bike wont work but a car will as as you still have one more set of wheels back to front keeping the car somewhat straight.